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OTL Asylum: RE: Futterman OTL3 - R29 gets very hot by therkild OTL, Output Transformerless Amplifier User Group. |
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In Reply to: RE: Futterman OTL3 - R29 gets very hot posted by airheadair on April 13, 2020 at 22:42:31:
Hi
No I ended giving up and handled them back to my friend.
Whenever I got one problem solved, the next appeared. Example, during trimming of the voltage levels in one of them, I noticed a significant change in current draw when I inserted my voltage meter probes in the test socket. A modern digital voltmeter in the meg. ohm category shouldn't influence a circuit causing it to draw more amp. Likely a damage in the print. I simply couldn't get to a point where they were stable.
My friend is currently doing a full rebuild, including changing them to PL 519 tubes. He's been designing and constructing tube amps for 30 years so he's far more capable of diagnosing why they behave like they do.
Will be interesting to hear them once he get them up and running.
Regards
Thomas
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Topic - Futterman OTL3 - R29 gets very hot - therkild 13:29:51 02/27/20 ( 9)
- RE: Futterman OTL3 - R29 gets very hot - therkild 01:32:28 03/2/20 ( 0)
RE: Futterman OTL3 - R29 gets very hot - rogerh113 06:43:09 03/1/20 ( 0)
RE: Futterman OTL3 - R29 gets very hot - therkild 11:35:25 02/28/20 ( 5)
- RE: Futterman OTL3 - R29 gets very hot - airheadair 22:42:31 04/13/20 ( 2)
- RE: Futterman OTL3 - R29 gets very hot - therkild 04/15/20 03:25:01 04/15/20 ( 1)
- RE: Futterman OTL3 - R29 gets very hot - rhinohifi714 14:02:04 04/29/20 ( 0)
I'd be looking at the screen regulator for that circuit. - Ralph 14:21:25 03/3/20 ( 0)
RE: Futterman OTL3 - R29 gets very hot - rogerh113 07:48:18 03/2/20 ( 0)
RE: Futterman OTL3 - R29 gets very hot - rogerh113 07:36:39 02/28/20 ( 0)